In an effort to motivate contractors to complete construction projects early on high-impact highway pavement construction projects, state transportation agencies (STAs) including TxDOT have often used incentive/disincentive (I/D) contracts. However, determining I/D rates is extremely difficult due largely to the lack of systematic methods for helping STAs determine effective I/D rates. The primary goal of this project is to develop a novel framework for determining the most realistic and economical I/D dollar amounts for high-impact highway improvement projects. To achieve its goal, this project proposes an integration analysis including project schedule and the lower and upper bounds of the I/D contract. The lower bound is the contractor's additional cost of acceleration, and the upper is the total savings to road users and to the agency. The study data were gathered using Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) software. These data were then grouped by four different types of pavements, namely Joint Plain Concrete Pavement (JPCP), Continuously Reinforced Concrete Pavement (CRCP), Hot Mix Asphalt (HMA), and Milling and Asphalt Concrete Overlay (MACO). With these data, a series of regression analyses were carried out to develop predictive models for the validation of time-cost tradeoff to determine I/D lower bound. Road user cost and agency cost savings were quantified using CA4PRS to develop lookup tables to determine I/D upper bound. Adjustment of contractors' additional cost of acceleration with Level of Service (LOS) and total savings adjustment using Net Present Value (NPV) were incorporated in the research study to calculate point based estimates of I/D for lower and upper bound, respectively. Lastly, case studies on real world projects were conducted to evaluate robustness of the model. The research results reveal that the predictive models give appropriate results for the case studies in determining the I/D dollar amount for the lower and upper bound. This study will provide the research community with the first view and systematic estimation method that STAs can use to determine the most economical and realistic I/D dollar amount for a given project-an optimal value that allows the agency to stay within budget while effectively motivating contractors to complete projects ahead of schedule. It will also significantly reduce the agency's expenses in the time and effort required for determining I/D dollar amounts.
